Relationship between smoking and sleep apnea in clinic population

STUDY OBJECTIVE: To examine the relationship between smoking and sleep apnea. DESIGN: Cross-sectional case study SETTING: University hospital sleep clinic PATIENTS: We studied 3,509 patients. INTERVENTIONS: None MEASUREMENTS AND RESULTS: Smoking history (past, present, never-smoker, pack-years of smoking) and nocturnal polysomnography was obtained in all patients. Data analysis was performed as follows: Patients were divided into groups based on apnea seventy (to compare smoking), and on smoking seventy (to compare apnea hypopnea index - AHI). The relationship between smoking and apnea was examined using univariate, multivariate, and logistic regression analysis. We found that patients with AHI greater than 50 were heavier smokers than nonapneic controls (14+/-17 vs. 10+/-17 pack-years, respectively). Conversely, heavy smokers had higher AHI than non-smokers (26.3+/-28.3 vs. 19.7+/-23.9, respectively). There was no significant relationship between AHI and smoking in multiple regression analysis. Although logistic regression revealed that heavy smokers (>30 pack-yrs) had almost twice the risk of having AHI greater than 50 compared to nonsmokers, the odds ratio fell below one after adjusting for age, BMI, and gender. CONCLUSIONS: In our patient population, smoking is not an independent risk factor for sleep apnea after adjusting for other confounding variables.